An ore contains $23 \%$ copper. To get $69 \text{ kg}$ of copper, the quantity of the ore required is: (in $\text{ kg}$)

When a number is divided by $12$,the quotient is $\frac{1}{4}$ of another number. By what percentage is the first number greater than the second number?

Half of $1$ per cent written as a decimal is

$60 \%$ of $264$ is the same as

$A$'s salary is $50 \%$ more than $B$'s. How much percent is $B$'s salary less than $A$'s?

Six-elevenths of a number is equal to $22 \%$ of a second number. The second number is equal to one-fourth of a third number. The value of the third number is $2400$. What is $45 \%$ of the first number?